Relay timing circuits



June 8, 1965 R. LUCE RELAY TIMING CIRCUITS Filed Oct. 26, 1962 11! 1 v E fi T 7 to V Fig.7

P4 P2 20 P1 Fig.2

ATTORNEY United States Patent 3,188,527 RELAY TIMING CIRCUITS Rudolf Luce, Ditzingen, Wurttemberg, Germany, assignor to International Standard Electric Corporation, New York, N.Y a corporation of Delaware Filed Oct. 26, 1962, Ser. No. 233,382

Claims priority, application Germany, Nov. 3, 1961,

St 18,510 Y 5 Claims. (Cl. 317-141) This invention relates in general to relay timing circuits and in particular, to circuits designed to provide slowatooperate and slow-to-release relay functions.

In the past, capacitors have been used in conjunction with relays to delay the operation or release of the relay when a timing function is desired. A drawback in the use of capacitors in such relay timing circuits is caused by the fact that the time delay varies as a function of the supply voltage.

Timing relay circuits comprising biasing coils have been used to make the time delay interval independent of supply, voltage variations. Such a circuit is disclosed in the recently issued United States Patent No. 3,117,254 entitled Timing Circuit Consisting of a Relay and of "a Parallel, Connected Capacitor filed by the applicant herein and assigned to the assignee of this invention. The patent teaches a timing relay circuit that either uses a permanent magnet biasing means or else uses a separate supply voltage to energize a biasing winding to obtain independence from variations in the supply.

It is not always possible to have two separate supplies. In addition, even where it is possible to have separate supply volt-ages it is more economical and practical to use the same supply to energizethe bias winding. Circuits are known wherein the bias supply is derived from the same source as the supply used for energizing the operating windings. These timing relay circuits utilize two oppositely wound biasing windings connected to the common power source that is used to energize the operating coils. One of the bias windings or coils is connected to a constant voltage device. The other bias winding is connected to the power source without regulation and accordingly, the biasing is designed to vary inversely with the variations in the power supply. Such a design requires two biasing coils which increase the cost, size, and the weight of the timing relay. In addition, two biasing coils have to be adjusted to obtain the desired timing characteristics.

Accordingly, it is an object of this invention to provide new and unique timing relay circuits.

It is a related object of this invention to provide timing relay circuits that are independent of variations in the operating power.

It is a more particular object of this invention to provide relay timing circuits that are independent of power supply variations and that utilize only one source of power and only one biasing winding.

According to one embodiment of this invention a timing relay is provided having two oppositely wound operating coils. The first operating coil is connected in series with an operating switch, which when closed completes a circuit from battery through the first coil to ground. The second operating coil in series with a capacitor bridges the first operating coil. A single biasing winding is provided. One side of the biasing winding is connected through a voltage divider to a regulated voltage obtained from the common source. The other side of the coil is connected with no voltage regulation to the common power source through a voltage divider. The biasing is arranged so that it varies inversely with the variations in the supply.

These and other objects and features of the invention and the manner of obtaining them will become more ap- 3,188,527 Patented June 8, 1965 parent, and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, in which:

FIG. 1 shows schematically a prior art timing relay circuit; and

FIG. 2 shows schematically a timing relay circuit that is a preferred embodiment of the present invention.

Referring to FIG. 1, therein is shown, schematically, a timing relay circuit comprising four coils. Coils I and II are the operating coils wound in opposite directions. One side of coil I is connected directly to a common power supply indicated by the negative sign. The other side of coil I is connected to switch a, shown in an open position. The other side of switch a is connected to ground. 7

One side of operating coil II is connected to the junction of coils I and switch a. The other side of coil II is connected to the common power source through a timing capacitor C.

Two oppositely wound biasing coils III and IV are provided. Coil III is connected between ground and a variable tap on potentiometer P1. The potentiometer P1 is connected between the common power source and ground. Coil IV, the second bias coil, is also connected between ground and a variable tap on a potentiometer which is connected on one side to ground and on the other side to the common power supply through a dropping resistor R1.

Means are provided for regulating the voltage across potentiometer P2. In greater detail, a regulating device, such as zener diode ZD, is lbridged across the potentiometer P2.- Thus, coil IV is supplied with a regulated voltage.

In operation, when switch a is closed, operating circuits are completed that extend from battery (common supply) through coil I and switch a to ground. The operating circuit also extends from battery through capacitor C, coil II and switch a to ground.

As indicated by the arrows juxtaposed to the coils I and II, they are wound in opposite directions and hence, produce oppositely directed magnetomotive forces when subjected to currents having the same directions.

When switch a closes the current that flows from battery through capacitor C and coil II builds up much faster than the current that flows through coil I. This difference in initial current flow is, of course, due to the capacitor C. The coil II magnetomotive force opposes the actuation of the contact armature (not shown). The coil I magnetomotive force actua-tes the contact armatures to operate. Since the coil I magnetomotive force is opposed by the initially larger coil II magnetomotive force, the relay does not operate until the coil II force diminishes sufiiciently. The current through coil II will fall olI as eapacitor C charges. Thus, the operation of the relay is delayed until capacitor C charges sufiiciently.

When switch a is opened the relay release is delayed by the discharge of capacitor C which acts as a power source for the discharge current that flows from capacitor C through coils II and I in series to negative battery. Thus, the discharge current in coil I flows in the same direction as the operating cur-rent and the discharge current in coil II flows in a direction opposite to the original operating current. Therefore, the flux generated by coil II aids the flux generated by coil I thereby maintaining the relay operated for a definite time period.

Both the delay time periods are functions of the component values and of the value of the supply voltage when switch a is operated. Mean-s are provided for making the time delay increments independent of the supply voltage. In greater detail, FIG. 1 shows two bias coils, III and IV. Coil III is connected to the tap on potentiometer P1. Coil IV is connected to the tap on potentiometer P2. As can be seen by the arrows juxtaposed to the coils, coil IV is wound in the same direction as is coil I and coil III is oppositely wound. This tap can be adjusted, for example,

cause the relay to operate if there is any current flowing more flux than is required to cancel the flux of coilIV.

In this case, some of the flux of coil III would counteract the flux of coil I and thereby compensate for the higher supply voltage. I v i I Ina similar manner, when the supply voltage decreases,

the flux generated by coil III is less than the flux generated by coil IV. Thus, some of. the coil IV flux aids the flux of .coil I to maintain the same time delay for the release of the relay after operation of switch a, notwithstanding the decreased supply voltage. V a

The system of ascertaining that the time delay is independent of the supply voltage atforded by the relay circuit of FIG. 1 requires two biasing coils. essarily increases the size, weight and cost of the relay; FIG. 2 shows how the same independence of supply voltage can be obtained using only one bias coil,;coil V. To expedite the explanation, FIG; 2 usesthe same reference designations'as areused' in FIG. 1. In fact, the only difference between FIG. 1 and FIG. 2 is in the biasing circuit where coils III and IV are replaced by the single coil V. Coil V is connected between the taps on potentiometers P1, P2. The tap of potentiometer P1 is adjusted first to connect coil V to ground. Then potentiometer P2 is adjusted so that coil V almost maintains the relay operated. It should be noted that the flux in coils I and V aid each other. flows in coil V when the" supply voltage is at the specified value. If the voltage increases, flux opposing the coil, I flux is generated in coil V. Similarily, if the supply voltage decreases, flux aiding the coil I flux is generated in coil The fourth coil ne'c- V. Thus, coil V ascertains that the time delay is independent of variations in supply voltage.

While the principles of the invention have been described above in connection with specific apparatus and applications, it is to be understood that this description is made only by way of example and not as a limitation on the scope of the invention. 7

I claim: V i V 1. A timing circuit comprising a'relay associated with a capacitor in'an electrical circuit, said relay consisting of first and second oppositely Wound ope-rating coils and one bias coil, switch means for completing an operating circuit to said first and second operating coils, means for connecting'said first operating coil between said switch means and a common power source, means forcoupling said second operating coil to said capacitor in a series circuit, means for connecting said series circuitacross said 7 first operating coil, means for adjustablyiconnectin-g one side of said bias coilto said common power source, means for connecting said other side of said bias'coil to a supply of regulated voltage and means for supplying said regulated voltage from said common power source. j 2. In the timing circuit of claim 1 wherein said. means for connecting said bias coil to said common power source comprises a first potentiometer; i

3. .In the timing circuit of claim 2. wherein'saidmeans for connecting said bias coil to'said regulated voltage comprisesa second potentiometer.

4.- In the timing circuit of claim 3 wherein said second potentiometer is bridged by a zener diode. v 5. In the timing circuit of claim 4 wherein resistor means are providedrfor connecting said zener diode to said common power source.

Potentiometer P1 is then adjusted'until no current 7 7 References Cited by the Examiner UNITED STATES PATENTS 3,087,109 4/63 Bowers 323--75 X 3,117,254 1/64 Luce 317141 3,133,233 5/64 Peterson et a1 '317'155.5 X

SAMUEL BERNSTEIN, Primary Examiner. 

1. A TIMING CIRCUIT COMPRISING A RELAY ASSOCIATED WITH A CAPACITOR IN AN ELECTRICAL CIRCUIT, SAID RELAY CONSISTING OF FIRST AND SECOND OPPOSITELY WOUND OPERATING COILS AND ONE BIAS COIL, SWITCH MEANS FOR COMPLETING AN OPERATING CIRCUIT TO SAID FIRST AND SECOND OPERATING COILS, MEANS FOR CONNECTING SAID FIRST OPERATING COIL BETWEEN SAID SWITCH MEANS AND A COMMON POWER SOURCE, MEANS FOR COUPLING SAID SECOND OPERATING COIL TO SAID CAPACITOR IN A SERIES CIRCUIT, MEANS FOR CONNECTING SAID SERIES CIRCUIT ACROSS SAID FIRST OPERATING COIL, MEANS FOR ADJUSTABLY CONNECTING ONE SIDE OF SAID BIAS COIL TO SAID COMMON POWER SOURCE, MEANS FOR CONNECTING SAID OTHER SIDE OF SAID BIAS COIL TO A SUPPLY OF REGULATED VOLTAGE AND MEANS FOR SUPPLYING SAID REGULATED VOLTAGE FROM SAID COMMON POWER SOURCE. 